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Edexcel A-Level Mathematics A2 S3.3.4 Confidence Limits for a Normal Questions

Practise forming Normal-mean confidence intervals with known variance, standard errors and summary statistics using verified Edexcel IAL evidence.

Syllabus
First assessment 2019
Course
Mathematics YMA01
Level
A2

Exam points

  • use the correct z value and standard error to form a confidence interval for a mean
  • compute x̄ from summary data before applying x̄ ± zσ/√n
  • explain that CLT is unnecessary when the original population is Normal

Edexcel A-Level Mathematics A2 S3.3.4 Confidence Limits for a Normal Questions question 1

[Maximum number: 4]

A garden centre sells bags of stones and large bags of gravel.
The weight, X kilograms, of stones in a bag can be modelled by a normal distribution with unknown mean μ\mu and known standard deviation 0.4

The stones in each of a random sample of 36 bags from a large batch is weighed. The total weight of stones in these 36 bags is found to be 806.4 kg

Find a 98% confidence interval for the mean weight of stones in the batch.

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